The mountains near here rise as jagged and unforgiving obstacles on the horizon for immigrants and smugglers who cross the border by moonlight and make their way northward along the foothills, stopping in the cypress groves for rest. It’s a natural passage and the easiest route to travel.

But it was also here, on April 8, that a group of what was described as four white men wearing camouflage opened fire on a packed truck carrying immigrants illegally into the country, killing two of them. The victims, Gerardo Perez-Ruiz from the central Mexican city of Toluca and another man believed to be from Guatemala, were part of a group of 20 to 30 immigrants driving through a remote desert wash near Eloy when the group of gunmen suddenly appeared.

According to statements provided by five surviving immigrants, the gunmen yelled, “Alto!” — “Halt!” — as the truck neared, then fired their weapons before disappearing without another word into the pre-dawn darkness.